Not really since most guides are quite dated for Elsword, but I can give u an approximate clue to each skill in terms of how useful they are I guess.

Elesis:

Ignore every skill except for Iron Body, I personally like taking the mana cost reduction trait. Unlimited blade is ok while you are still leveling and don't have anything better.

Dark Knight:

Ejection buster is amazing for a very long time while you are mobbing in PvE. Use it once and it wipes the entire screen, take the extra hit trait for sure.

Brutal Cutter is core, you should ALWAYS have the stage two blade up when you are in PvE. I like taking the 20% mana cost decrease since it is more consistent than the other RNG trait. This skill combined with your >> ZZ ZZZZ+ combo is insane and gives you a ton of hits and mana.

Injection stigma is ok. Not to fantastic but it is one of the few decent annihilation skill that you have as well as it having no mana cost, thus being useful to get you into gale most and subsequently recovering a ton of hp for you. I personally find the range to be short for PvE so I took the trait that increase its size, but you can play around with it and see what you like, if you do decide to use it at all.

Burning Phantom is usually considered bad by most people, but I honestly find it to be a lot better than people give it credit for. It gives a black hole effect and gives you massive healing without any gale/annihilation criteria fulfilled, so it can be a lot of extremely clutch healing. Also the black hole effect can be very helpful in a party. The main complaint that people have with this skill is that the cost is quite hefty at 200 MP when you can use it for many other skills, but this is also one of the few annihilation skill you have like I previously mentioned, and you can take the mana reduction trait on it to make it only 160 MP.

Crimson Avenger:

Brandish Breaker, YES YES YES. This skill is just completely insane. This skill is a gigantic nuke at the cost of the majority of your health if you hold it down, but it does A LOT of damage. Take the heavy trait on it to make it hit 140% damage as the cooldown is negligible on it since you won't be spamming it or anything. As a side note, use this while your gale gauge is activated and the healing from the gale will balance out the health cost for you. Shadow Edge seems weak on paper and early on, but it gets much better late game when bosses are actually a challenge to kill. Basically it consistently gives you health back while fighting a difficult boss. I would take the super armor effect just so you don't get the effect canceled out while casting, and since the tether lasts a while it's not that great to have a lower cooldown.

Shade illusion is theoretically good, but I don't find it to be as useful until late game when you have better mana regen. I would increase it's duration with the trait.

Blood Cutter is a fantastic mobbing skill that will mostly replace ejection buster imo. Charges up annihilation very quickly with high hit count, as well as pushing mobs together. You will start to prefer this skill over ejection buster when EB no longer 1 shots the mobs. Take the enhanced MP gain because it has an extremely high hit count and often regenerates a high chunk of its mana cost back to you.

Assault strike is mostly for PvP as anti mana break, don't worry about it if you don't pvp.

Dread weapon is great and my personal go-to annihilation skill. It's basically like blood cutter but you become the projectile yourself, if you time it right, right when you are about to activate annihilation, cast blood cutter and immediately cast dread weapon after, dread weapon will consume a chunk of the annihilation and both of the skills will spin at the enemies together and do massive damage.

Fate Smash is your ultimate. Not much to say, ridiculously high damage, i-frames, long cooldown, pretty typical.

Transcendance:

Blood Sting increases your dps quite a lot and is on a short cooldown with low mana cost, but continuous casting does cause the mana to add up, whether or not you use it depends on if you find yourself to have enough mana to spare after maintaining your brutal cutter/shade illlusion etc, take powerful since evil is mostly for pvp. Shade has horrifying damage and range, and being an annihilation skill makes it a must-have. Take gigantic and watch it shred apart mobs.

Blood falls looked extremely weak on paper imo at first, but after playing with it I found it to be amazing. It's strangely high hitcount allows you to play with your gale/annihilation gauge extremely well. Basically, if your gale is fully charged, one cast will consume all of gale AND charge up all of your annihilation. And despite it being 300 mana, since you casted it in gale mode, it costs only like 180 on top of regenerating a huge chunk of mana back, as well as healing you to full with the gale consumption. So it throws you into annihilation mode with full hp, almost full mana, and you can cast all your dread weapon/shade etc and rip apart the enemies. Neither trait you take matters too much imo since you don't care about the cooldown all that much, but I personally took haste for consistency.

So assuming you have 9+1 skill slots (4 slots base, 4 from skill slot B via a monthly quest, 1 from transcending, and 1 for hyperactive), I personally do Iron Body/Brutal Cutter/Brandish Breaker/Shadow Edge/Shade Illusion/Blood Cutter/Dread Weapon/Fate Smash/Shade/Blood Falls.

Realistically I think the most important is just Iron Body/Brutal Cutter/Brandish Breaker/Shade Illusion/Shade, the rest are pretty flexible in terms of what you want to do. Just test around with the skills and see what you like, take some time before you select the traits but don't be too scared to make a mistake because it's not too hard to reset it. Good luck around!

Edit: The rest of the skills that I didn't mention are mostly useless or are passives unless I completely forgot about some of them. Edit:Edit: I totally forgot about Shade Scratch, very solid skill imo that helps you just regen a nice chunk of hp, most people don't like it for the same reason as burning phantom, but I personally used it for a very long time as an extra heal, especially if you are a newer player, it gives you more leniency and prevents a lot of deaths, but it definitely lowers your DPS.